Preparation

Piperine is commercially available. If desired, it may be extracted from black pepper using dichloromethane.[3]

[edit] Biological activity

The pungency caused by capsaicin and piperine is caused by activation of the heat and acidity sensing TRPV ion channel TRPV1 on nociceptors (pain sensing nerve cells).

Piperine has also been found to inhibit human CYP3A4 and P-glycoprotein, enzymes important for the metabolism and transport of xenobiotics and metabolites.[4] In animal studies, piperine also inhibited other enzymes important in drug metabolism.[5][6] By inhibiting drug metabolism, piperine may increase the bioavailability of various compounds. Notably, piperine may enhance bioavailability of curcumin by 2000% in humans.[7]

In February 2008, researchers discovered that piperine can stimulate pigmentation in the skin.[8][9]

Due to its effects on drug metabolism, piperine should be taken cautiously (if at all) by individuals taking some other medications.[citation needed]

Piperine was first discovered by Hans Christian Ørsted in 1819.[citation needed]

Table 1. Substances for which piperine has been directly shown to increase bioavailability.
barbiturates
beta-carotene
coenzyme Q10 (CoQ10)
curcumin (extract from turmeric)
dapsone
ethambutol isoniazid
nalorphine
phenytoin
propranolol
pyrazinamide
rifampicin selenium (from selenomethionine)
sulfadiazene
theophylline
vitamin B-6 (pyridoxine)
glucose (absorption increased)
amino acids (absorption increased)

A far larger list could be compiled of substances (including drugs and dietary substances) whose bioavailability is assumed to be altered by piperine due to the known effects of piperine on proteins that metabolize or transport these substances.


Table 2 lists some of the drugs that fall into this category. It would be useful to have an analogous list for dietary substances, but in most cases the data do not exist.
Table 2. Metabolizing enzymes inhibited or induced by piperine, and a few of the substances whose bioavailability is affected by these enzymes. Metabolizing Enzymes: CYP1A1, CYP1B1, CYP1B2, CYP2E1, CYP3A4


Drugs: acetaminophen, alfentanyl, amiodarone, amlodipine, astemizole, atorvastatin, barbiturates, benzodiazepines, buspirone, Cafergot, caffeine, carbamazepine, cerivastatin, chlorpheniramine, chlorzoxazone, cimetidine, ciprofloxacin, cisapride, clarithromycin, cocaine, codeine, cyclosporine, dapsone, dextromethorphan, diethyl-dithiocarbamate, diltiazem, disulfiram, efavirenz, enflurane, eplerenone, erythromycin, estradiol, ethanol, felodipine, fentanyl, finasteride, fluconazole, fluvoxamine, gestodene, Gleevec, glucocorticoids, haloperidol, halothane, hydrocortisone, indinavir, irinotecan, isoflurane, isoniazid, itraconazole, ketoconazole, LAAM, lercanidipine, lidocaine, lovastatin, methadone, methoxyflurane, mibefradil, mifepristone, modafinil, nefazodone, nelfinavir, nevirapine, nifedipine, nisoldipine, nitrendipine, norfloxacin, norfluoxetine, odanestron, phenobarbital, phenytoin, pimozide, pioglitazone, progesterone, propranolol, quinidine, quinine, rifabutin, rifampin, ritonavir, salmeterol, saquinavir, sevoflurane, sildenafil (Viagra), simvastatin, sirolimus, St. John’s wort, tamoxifen, taxol, terfenadine, testosterone, theophylline, trazodone, troglitazone, verapamil, vincristine, zaleplon, zolpidem


Other actions of piperine

Aside from its effects on bioavailability, piperine has a number of other actions in the body. (It is suspected, but not proven, that some of these actions result from piperine’s effects on the bioavailability of other substances.) These actions include:

* Increasing the brain’s production of beta-endorphins
* Pain relief
* Increasing the brain’s production of serotonin
* Anticonvulsant, anti-epileptic action
* Increasing the adrenal glands’ production of epinephrine (adrenaline)
* Altering contractions in the upper and lower digestive tract
* Reducing the stomach’s production of acid (for about 1 hour)
* Decreasing ulceration of the stomach
* Increasing the pancreas’s production of digestive enzymes (amylase, lipase, trypsin and chymotrypsin)
* Stimulating production of melanin
* Reducing inflammation due to irritation or allergy
* Relieving asthma symptoms

These actions have been deduced from lab experiments, not clinical studies, and so the dosages required to achieve them are not known.

How the body controls access to its cells
The body has several major mechanisms for controlling the exposure of its cells to nutritional and other substances. Four of these mechanisms are of interest with regard to piperine: metabolic conversion, assisted absorption, assisted exclusion, and solubilizer attachment.


Metabolic conversion involves the use of enzymes to chemically convert substances to different substances that may be less active and, in any case, are more easily carried in blood to the kidneys for excretion. The original substances are called ‘substrates’ of the enzymes; after conversion they are called ‘metabolites’. For example, an enzyme called ‘aromatase’ converts the substance testosterone into estradiol. Testosterone is a substrate of the aromatase enzyme; estradiol is a metabolite of testosterone. Although estradiol is itself an important hormone in the body, it also serves as an excretable form of testosterone. Other enzymes convert estradiol into even more easily excreted forms, such as estriol.

Assisted absorption, the second method for controlling the exposure of cells to substances, involves the use of transporter proteins in the cells of the digestive tract. These proteins actively transport substances into cells of the intestinal lining; from there they can be transferred to the blood. Assisted absorption is particularly important for ensuring that essential amino acids are available in adequate amounts.

Assisted exclusion involves the use of transporter proteins that ‘pump’ certain substances out of cells, whereupon they can be taken away by the blood. While the activities of these pumps can protect cells from toxic overloads of many substances, they can also spoil the efficacy of otherwise beneficial drugs and supplements by pumping these substances out of the cells before they can act. One of the most important such ‘pump’ proteins is p-glycoprotein, which is found in the membranes of cells in the intestines, brain, liver, pancrease, kidneys, and other tissues.

Solubilizer attachment prevents substances from entering cells by linking them chemically to a highly water-soluble substance. Not only does this alter the biological activities of the substances in question, it also makes them unable to diffuse through cell membranes. One of the important solubilizers found in the body is glucuronic acid. Substances bound to this solubilizer are usually excreted either into the urine or into the small intestine, depending upon the nature of the substance.

How piperine increases the bioavailability of many substances

Piperine has the remarkable ability to manipulate all four of these mechanisms. It inhibits a number of enzymes responsible for metabolizing drugs and nutritional substances; it stimulates the activity of amino-acid transporters in the intestinal lining; it inhibits p-glycoprotein, the ‘pump’ protein that removes substances from cells; and it decreases the intestinal production of glucuronic acid, thereby permitting more of the substances to enter the body in active form. Consequently, some of these substances are able to reach, enter, and remain within their target cells for longer periods of time than would otherwise be the case. Of course, this can be a mixed blessing — if one is using a drug for which the therapeutic level is not substantially lower than the toxic level, piperine supplementation might raise the bioavailability of the drug until its intracellular concentration exceeds the toxic threshold. On the other hand, piperine supplementation can sometimes turn a marginally effective therapeutic substance into a highly effective one simply by increasing its bioavailability and intracellular residency time. A good example of this latter phenomenon is the use of piperine to increase the bioavailability of curcumin, a supplement with broad activity against cancers, inflammation and infections. A 20 mg dose of piperine can increase curcumin’s bioavailability twentyfold.

whoa..this stuff sounds interesting

there are several subtypes of cytochrome P450, each acting independently or in conjunction. the one that metabolizes tryptamines is CYP2D6, I believe. you may be able to inhibit CYP3A4 with piperine, which I think in turn downregulates CYP2D6.

I'm also highly interested in the Psychoactive Properties of Saffron.